Sender: <marv@lancaironline.net> (Marvin Kaye)
To: lml
Date: Tue, 01 Apr 2003 14:11:14 -0500
Message-ID: <redirect-2100866@logan.com>
From: "Metcalfe, Lee, AIR" <Lee.Metcalfe@jocoks.com>
Subject: RE: [LML] Re: IO-320 / Hartzell Prop Strange RPM Behavior (Long)
MIME-Version: 1.0
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Cy:

My A&P and I and Hartzell (Kevin Ryan) had several lengthy debates about the
effects of changing the engine oil pressure.  I was convinced that was the
cause, the A&P wasn't sure, but Hartzell explained that lack of sufficient
pressure couldn't be the cause, because with low oil pressure to the prop it
wants to go to low pitch/high rpm.  So in that case the RPM limiting factor
should be the pitch stops.  The new prop came from the factory with the
pitch stops set for the O-320 application, so they should be right.  Even
so, at Hartzell's suggestion, the A&P adjusted the pitch stops to increase
flat-pitch RPM by about 200.  The RPM will still not go above 2500 until
airspeed is over 140.  Hartzell says it has to be the governor that is
pulling the RPM down, but they can't figure why a newly overhauled governor
with the control stops set properly would do that.

Bill:

Maybe my description of where the temp & press taps are wasn't clear.  When
I got the plane, the oil pressure gauge (direct read) was tapped at the
front of the engine on the top right side of the case.  This is at the point
on the oil galley that is furthest from the pump and would probably have the
lowest pressure in the system, according to my A&P.  He moved the pressure
tap to the back of the engine at the "preferred" location, and put the temp
sensor where the pressure tap was.

I will be very interested to hear what Don has to say!

Thanks guys!

Lee